Anomaly detection in drilled shafts

Sarah L. Gassman, Richard J Finno

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


A series of impulse response tests using multiple geophones was performed to identify anomalies in drilled shafts. Testing was performed on drilled shafts at the University of Houston NGES to detect small anomalies and at the Texas A&M University NGES to detect gross anomalies. Both sites consisted of drilled shafts constructed with carefully controlled construction procedures and included known anomalies. The results of the impulse response tests were analyzed using a new technique based on composite geophone array analysis and numerical simulations. Differences in responses depending on the placement of the geophone on the shaft head surface were investigated and the ability to quantify the size and location of the planned anomalies was evaluated. Impulse response tests performed on the drilled shafts at Texas A&M showed that detection of severe defects caused by dynamic load testing was enhanced by the multiple geophone approach when resonances from the shaft toe could only be detected from certain geophone locations. However, the multiple geophone approach was unsuccessful in identifying the small anomalies, 2.54 cm thick rubber inclusions, in the Houston shafts.

Original languageEnglish (US)
Pages (from-to)221-234
Number of pages14
JournalGeotechnical Special Publication
Issue number93
StatePublished - Jan 1 2000

ASJC Scopus subject areas

  • Soil Science
  • Building and Construction
  • Architecture

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